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New 740 turbo prepump in my 1985 245T[240-260/1985] posted by Ted Y. on
Saturday, 18 July 1998, at 11:57 p.m.
Hello all,
Today, after much question-asking and part-searching, I finally installed a 740 turbo pre-pump in my 1985 245 turbo.
I had done this because I was getting an increasingly loud "buzzing" noise as the tank neared empty. I also noticed some hesitation/sputtering under full boost (not adjusted yet). Just about finished comllete major service (most importantly cap, rotor, plugs, wires, fuel filter, timing belt/tensioner, K&N air filter, oil filter, Castrol "Syntec" oil, added trans. fluid (put a little too much in), and some other few things I can't remember.
Well, the "buzzing" is still there. As far as I know, I did a good job. I cut the feed line 1 1/4 inch (as indicated by the "upgrade service bulletin" given to me. I inspected all hoses around the assembly for leaks, I removed (didn't replace) the wire screen inside the tank (the old thing was ripped in half, and the part that wasn't was COMPLETELY black and not permeable at all). The "o-ring" looked perfect, but I used RTV sealant around it anyway.
I took the car out for a test-spin. Though I still heard the "buzzing" at 1/2 tank, I noticed the hesitation seemed to be gone at full throttle in high RPM's.. At a stop, I held the brake (it's an auto), gave her gas (only climbed to 2000 RPM), and let her rip. Small burnout. Put her in first (manually), and shifted to second at 5000 RPM. Hmmm, better torque. Second to third. Still good torque and no more hesitations.
I was wondering what the heck that "buzzing" still is. I will se if the hesitation comes back as the tank nears empty. The buz is annoying, though.
Anyone have any ideas?
Please help!
Thanks,
Ted (Bundy) Y.
Re: New 740 turbo prepump in my 1985 245T[240-260/1985] posted by Ted Y. on
Sunday, 19 July 1998, at 12:42 a.m.
Me again.
I also noticed an occasional "smoke cloud" from the rear for the first few seconds under full boost. I am not sure what color, but I think it's white/grey. My piston compression is pretty much 155 on all 4 cyls (very good), and I do not need to add coolant or oil frequently (haven't had to yet).
After hard driving, the idle in "park" drops to about 750-800 RPM for about 10 seconds, then returns to normal (about 1000 RPM). I cleaned out the "idle air control valve" (this happened worse before, but went away after cleaning...seems to be back now). My mechanic-freind (from German Car Specialist) set the timing previously and hooked her up to an "exhaust gas analyzer". He said the emmisions were very low.
Hoped that may help.
Anybody out there have any advice? I'd really appreciate it.
Ted (Bundy) Y.
Re: New 740 turbo prepump in my 1985 245T[240-260/1985] posted by abe crombie on
Sunday, 19 July 1998, at 1:11 a.m.
Whining fuel pumps are to an extent a normal noise for fuel injected cars. The mounting of the pump uses rubber isoaltors to quiet it to some degree and those may have hardened. Another possibility on CI fuel system is the accumulator is stuck. This is the can that is next to fuel pump under car. Its purpose is to provide dampening of pump output pulses and acts as a storage chamber to retain adequate fuel press to prevent vapor lock on hot shutdown. Do you have any trouble with rough running or long cranking after you shut it down on a 95 deg + day?
The whisp of smoke may be purging of accumulated oil from crankcase vent system sending a bit of oil into intake plumbing, not unusual for a high miler in good shape even with minimal oil usage. Downside is that it might be turbo seals allowing a bit of oil to pass, don't worry, let it get worse if it's going to and then take action.
The occasional idle dip on throttle release is typical of B21FT engines. The throttle microswitch can cause it to happen if it is not closing when engine is hot intermittently.
My parents' 84 245T has done that idle dip thing on occasion all of its days and 180K miles. Won't do it repeatedly for me to get any meaningful readings as to what exactly is causing it. Hasn't worsened since first noticed years ago.